Wentworth, G. A. (George Albert), 1835-1906 · Boston, Ginn & company · leaf 231
et is desired, the target ismade fast with its horizontal line at 6^ feet from the lowerend. The back part of the rod is then moved up until thetarget is at the required height, and the reading is taken atthe side of the rod. When fully extended the rod is 12 feetlong. § 33. Difference of Level. To… … Fig. 43. B, but not necessarily on the line AB. Place the legs of thetripod firmly in the ground, and level over each opposite pairof levelling screws, successively. Let the rodman hold thelevelling rod vertically at A. Bring the telescope to bear up-on the rod (§ 8), and by signal direct the…
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